Graco is top of the line. Compare prices, you can get them online cheaper then at Home Depot. Sherwin Williams also has some good sales on them, but it's hit or miss.
NEVER pressure wash a house. This is one of the very worse things you can ever do to a house. No house was ever built to withstand a thousand, or several thousand psi of water trying to get into it!!! Pressure washers will blow out your seals, the caulking, and the paint. These things are there to keep water out. Once you force water past all your seals, you now have to deal with all that water that is now inside your walls, inside your soffits and behind your siding. Since these areas are protected from the sun and wind, they take a very long time to dry out. If it's warm at all, you have now created the perfect conditions for mold to grow. Food, moisture and warmth. It might take years, but eventually, you will have mold in there. You also might end up with termites and other types of bugs.
To properly clean a house, you need to buy a house cleaning detergent, spray it on the house, scrub it with a brush and wash it off with a hose. Then repeat until you get it clean.
Caulking is as good as what it costs. The better caulking costs more. It is more elastic, and it doesn't shrink as much over time. I like the 45 year stuff in white. Clear shrinks too much. Other colors are fine, but white is easy to see where it's applied and easy to paint over.
When applying caulking, be sure to go slow enough to get it into the cracks. Where you have existing cracking in your caulking, cut it with a sheetrock knife to create a V channel. No need to remove all of it, you just want to be able to fill the void. After you apply the caulking, I like to have a small cup of water handy. I dip my finger in the water and with a wet finger, smooth out the caulking. The results are flawless this way.
If the wood is holding the old paint good, you can paint right over the old. If the paint is coming off, or you have exposed wood, be sure to use a good quality exterior primer. Sherwin Williams has one specific for bare wood that is excellent. Zinsser makes the only other brand that I recommend for primer. Every other brand is junk!!!!
Once you are done caulking and priming, you will have no problem spraying. Just be sure to go slow enough to get good coverage. Also try to pay attention to your angle. You want to spray straight on. If you are at an angle, there will by areas on the Hardie that do not get as much paint as other areas. Especially behind the ridges on the boards. After spraying, I always inspect real close and usually have to touch up areas with a brush.
I also have the Bosch orbital sander from Lowes. It's a fair sander, but it's picky on the sand paper it likes. I've found that some sand paper, like Shop Smith, doesn't do well with sticking to the pad. Diablo seems to do the best, but it's nowhere near as good a sandpaper as Shop Smith. My next orbital sander will not be a Bosch becasue of the limited sand papers I can use on it.
